The present invention relates generally to the art of welding-type power supplies. More specifically, it relates to the control of welding-type power supplies.
Welding power supplies or systems are available for a wide variety of processes, and with a wide variety of sophistication. Welding-type power supply or system, as used herein, includes power supplies or systems that provide welding, cutting or heating power, and may include a controller, switches, etc. Traditionally, a good weld required an experienced welder, not only to properly execute the weld, but to properly select operating parameters (such as output voltage, current, power, pulse width, wire feed speed, etc.)
Now, robots are available that execute the weld. Also, operating parameters may be pre-determined and automatically implemented by a controller in the welding-type power supply. The automation is typically a software program that describes the output waveform, and is executed by a digital processor (microprocessors, DSPs, etc.). The program attempts to implement and improve upon the decisions that had been made by the experienced welder.
The programs and waveforms are xe2x80x9chard-codedxe2x80x9d, where a computer program includes typical control loops and procedures, such as xe2x80x9cif-then, xe2x80x9cgo-toxe2x80x9d, etc. For example, a decision would be on the order of: xe2x80x9cif the pulse phase has timed out and we are not in a short circuit and the trigger is still pulled then go to the background phasexe2x80x9d (written, of course, in a computer language such as xe2x80x9cCxe2x80x9d).
While how to write such a program is well known, it can be very difficult to modify such a program. Modification requires a review of each line of code, which is then carefully modified to give the desired result. Modification can, of course, cause unexpected consequences or require re-writing of entire sections. Such changes may be extremely time consuming, requires the person doing the modification to understand the software language and understand the particular interaction of all the hard coded lines in the system. Also, with each change, software bugs may be introduced and the program can require extensive trouble-shooting.
Welding automation is becoming increasingly sophisticated. This requires increasingly sophisticated control software, which only exacerbates the difficulty in updating or modifying a welding program. For example, a weld process might include peak amps, background amps, and a first ramp for the transition from background to peak. As the process control becomes more sophisticated, a second ramp from peak to background might be added, or the first ramp might be broken into two section with different slopes. It requires a substantial re-writing of the hard code to include these waveform segments. Then, if additional changes are made later, the code must be written again. Each addition to the code can lengthen the code, and make subsequent changes even more difficult.
Accordingly, a method and apparatus for controlling a welding-type power supply that allows for changing the waveform without requiring a lengthy and difficult re-writing of a program is desirable.
According to a first aspect of the invention a welding-type system includes a source of welding-type power and a controller. The controller has an output operatively connected to the source. The controller also includes a state-based control module, and/or a deterministic control module, connected to the controller output.
According to a second aspect of the invention a method of providing a welding-type output includes providing a source of welding-type power and controlling the source using a state-based control scheme.
The state-based control module includes software instructions and a digital processors and/or includes a state transition table stored in a spreadsheet data base, where a subsequent state and a current state are represented by data from the spreadsheet in various embodiments.
A feedback circuit is connected to the source and the controller and the state-based control module is responsive to the feedback circuit in another embodiment.
One or more welding peripherals, such as a wire feeder or robot, are operatively connected to the controller output in other embodiments.
The current state is represented by data in a first line of a spreadsheet and a state-ending event is indicated by a second, perpendicular, line of a spreadsheet, and the subsequent state is determined by the intersection of the first and second lines in another embodiment.
The data includes addressing data and/or parameter data in other embodiments.
According to a third aspect of the invention a method of controlling a welding-type system that operates in a plurality of states includes determining the present state of the system and determining at least one condition in which it is desired to end the state. The system is monitored for the existence of the at least one condition and a subsequent state to enter is selected from the plurality of states if the at least one condition exists. The selection is responsive to the at least one condition.
The at least one condition is a plurality of conditions, and the selecting is responsive to which of the plurality is met, and in order of first occurrence followed by priority, in an alternative.
The present state of the system includes correlating to a first set of data in a database, and/or determining at least one condition in which it is desired to end the state includes retrieving data from the first set of data, and/or selecting includes accessing a subset of the set of data in various alternatives.
The existence of the at least one condition includes monitoring at least one of timeouts and feedback in another embodiment.
Other principal features and advantages of the invention will become apparent to those skilled in the art upon review of the following drawings, the detailed description and the appended claims.